This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Project Description: The objective of this trial is to examine the long-term effects of a diet low in carbohydrates, as compared to one low in fat, on CVD risk factors, including blood pressure (BP), body weight and composition, serum lipids, plasma glucose, insulin, adipocytokines (adiponectin, leptin, resistin), and C-reactive protein (CRP) among obese adults. This study is a randomized controlled trial with a two-arm, parallel design. Using a stratified, blocked randomization scheme, eligible participants are assigned to either a low-carbohydrate intervention diet or a low fat control diet (instructions for each group will include intensive one-on-one counseling with a dietitian every week for 4 weeks followed by 10 biweekly sessions and 6 monthly sessions). This trial has 80% statistical power to detect clinically important changes in CVD risk factors. In order to conduct the trial, we will recruit 130 study participants (n=65 in each group) with a body mass index (BMI) of 30-45 kg/m2 using mass mailings, workplace screenings, community health fairs, and media advertisements in the Greater New Orleans, LA area;randomize the eligible participants to either a low-carbohydrate intervention diet for 12 months or a low fat diet for 12 months;provide diet instructions for each participant including intensive one-on-one counseling with a dietitian for a total of 15 sessions over 12 months;measure CVD risk factors (systolic and diastolic BP, body weight, body composition, waist circumference, lipid profiles, glucose and insulin levels, and levels of CRP and adipocytokines) in all participants at baseline, 3, 6, and 12 months of follow-up;and examine the differences in these risk factors among persons assigned to the low-carbohydrate intervention compared to those assigned to the low fat intervention.